The war started after years of problems between the British Empire (The Redcoats) and the colonists of North America, especially after the French and Indian War. There were 13 colonies, and the colonists (people living in the colonies) did not like many of the actions of the British government. For many years the British government decided which countries could trade with the colonies, instead of letting the colonies decide for themselves. Many colonists wanted free trade.
In 1765, the British Parliament needed money for the French and Indian War, and passed a law called the Stamp Act. This law said that colonists had to buy stamps for legal papers, newspapers, and even playing cards, as other British people did. The money from the stamps went to the king. The colonies did not follow this law. The colonies kept refusing to do what the king wanted. The Boston Tea Party and Boston Massacre caused people to become more angry about the situation. The British sent more soldiers to keep control of the colonies and sometimes had to fight. In 1774, the British passed the Intolerable Acts.
Not all colonists wanted to leave the British Empire. The Loyalists, or Tories, stayed loyal to Great Britain. They were not going to change their views. The Patriots, or Whigs, wanted independence. Before the Revolutionary War, most people in America were Loyalists; but after it, most people were Patriots.
Many colonists wrote letters showing how they felt. Thomas Paine wrote “Common Sense,” a famous pamphlet about independence from Britain. Other colonial leaders, such as Benjamin Franklin, John Adams, and Thomas Jefferson, wanted independence.
(edited from : source)